Stupid question,but......

[94tang]

What is the purpose of Friction Modifier in the rear diff.?

 

[408stroker5.0]

For limited slip/posi rear end's with clutch pack's. Basiacally without the fric. modifier the clutch pack's make a bunch of annoying racket when turning, mainly because there causing friction against each other. Fric. Modifier is an additive that quiet's the chattering down, by allowing the clutches to slip a bit, is really all there is too it. It also increases the life of the clutches if moderate amount's of fric. modifier is used. Don't put too much though, or the clutches will end up slipping too much and you won't have much of a posi left.

 

[89MustangGX]

It allows the clutches in the limited slip to slip some. It's purpose is to increase longevity of the limited slip unit and probably makes it a little more street friendly as well.

 

[DropTopR]

It's to help the clutches in the diff to operate smoothly, and to wear evenly. A lot of synthetic gear lube already has some type of modifier already built into it.